Actually, a small generator is not a bad idea at all. When not being used for R/C, you can use it in emergencies if power goes out. 800W is not that much, but enough for lighting or maybe even heating the house (only if gas heat where it just needs power for ignition and the blower).
A regular generator produces 120v, which is stepped down to 12v via a PS, then stepped back up for whatever the charger needs. Why not cut out the middle-man and produce 12v right at the generator? Since only ~200w is needed for almost all but the strongest chargers, a weedwacker engine running a car alternator to produce the needed 12v. Put a 0.5F cap on the output to smooth the DC pulses (car alternators are actually three-phase generators rectified via bridge or fullwave diodes).
